The invention relates generally to pumps, and more specifically to a very long life ferrofluid sealed and lubricated piston pump for use with heat pipes.
Heat pipes are used to transport large amounts of heat, or thermal energy, over short distances. Among other uses, they provide a generally reasonably-sized means for transferring waste heat from thermodynamic processes to heat sinks that, for a variety of reasons, cannot be placed nearer to the site of the thermodynamic activity. Their use is particularly applicable to spacecraft.
Heat pipes use successive evaporation and condensation of a working fluid to take advantage of the high heat of vaporization of most fluids in order to absorb large amounts of heat for transporting. Heat pipes typically use capillary forces, through a wick, to return condensed working fluid, or condensate, from a heat pipe condenser section, where transported thermal energy is given up at a heat sink, to an evaporator section, where the thermal energy to be transported is absorbed.
Unfortunately, heat pipe capillary wicks develop pumping pressures sufficient to transport heat only over limited distances. Future space missions will require transport distances beyond the limits of capillary pumping. A pump augmented capillary or a purely pump driven system are seen as viable solutions to this problem. At present, however, the life times of most mechanical pumps are limited by frictional wear of their moving parts. Life times of between 7 and 10 years will be required for most future space platform applications, a life time not possible with present pumps.
It is seen therefore that there is a need for a pump, suitable for use with space based heat pipes, that has a very long life.
It is, therefore, a principal object of the present invention to provide a pump, suitable for use with space based heat pipes, that has a very long life.
It is another object of the present invention to provide a pump that has a minimum of moving parts.
It is yet another object of the present invention to provide a pump that achieves its long life in part by minimizing friction between moving pump parts.
It is a feature of the present invention that it is also suitable for use in terrestrial heat pipe applications where long transport distances are required at relatively inaccessible locations.
It is an advantage of the present invention that its piston seals are generally self-repairing.